Process for carbonizing articles and apparatus for same



2 SHEETS-SHEET l.

Patented Aug. 24, 1926.

APPLICATION FILED JULY 26. 19|?.

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M. D. WLBUR, F. P. CANNON AND T. L MURPHY. PROCESS FOR CARBONIZINGARTICLES ANDbAPPARATUS EoR SAME.

PATENT orifice.

y UNITED STATES MERRITT D. WILBUR, OF ROCHESTER, FRANCIS P. CANNON, 0FSYRACUSE, 4AND THOMAS J. MURPHY, OF ROCHESTER, NEW YORK.

PROCESS FOR CARBONIZING ARTICLES AND APPARATUS FOR: SAME.

Specification of Letters Patent.

Patented Aug. 24, 1920..

Application led J'uly 26, 1917. Serial No.v182,926.

York, have invented a certain new and use.

ful Process for Carbonizing Articles and Apparatus for Same, of whichthe following is a specification.

This invention has for its object an apparatus and process ofcarbonizing articles, especially ferrous articles by applying quicklygenerated heat, as electrically generated heat, and thereby quicklyraising the temperature of the articles and the carbonizing materialabove the critical point so that the carbonizing is accomplished in arelatively short time as compared with several hours by other processes.The invention consists in the steps and operations and the apparatushereinafter set forth and claimed.

In describing this invention, reference is had to the accompanyingdrawings in which like characters designate corresponding parts in. allthe views.

Figures 1, 2 and 3 are diagrammatical views of different forms ofapparatus for carrying out our process and different ways of subjectingthe articles to electrically generated heat.

Fig. 4 is a plan View partly broken away,

of one form of the apparatus shown in- Fig. 1.

ig. 5 is a sect1onal view 'on l1ne 5 5,1

'is preferably electrically generated heat.

By the expression electrically generated heat is `meant heat generatedby the resistance of the carbonizing material to an electric currentpassing therethrough, or -heat generated by the resistance of anelectric heat unit, as a grid, around which the carbonizing medium isplaced and from which it receives heat by conduction, or heat generatedby an induced current generated in the carbonizing materialy and theferrous articles by the alternating magnetic iux.

Tn operation, the articles are packed in the carbonizing material, whichmay be pulverized bone dust, or carbonized oils in the form of smallpellets, and the carbonized material heated. The heat is brought quicklyto the desired temperature preferably above the critical point,ordinarily from 1600o to 1800o F. more or less, depending somewhat onthe structure and the size of the articles being treated.v Tt isbelieved that the electric current either passing directly through thecarbonizing material and articles being heated or generated or inducedtherein, facilitates the carbonizing process, and renders the productmore satisfactoryr in that it has a direct influence other than the meregeneration of heat.

The electrically generated heat maybe utilized conductively,convectively or inductively, in accordance with the apparatus employed.

The apparatus shown in Fig. 1, comprises a container having a lining 1of fire clay or some non-conductive and highly refractory material, andelectrodes 2, 3 exposed in the container on opposite sides thereof andbetween which are placed the articles 4L- to be carbonized, and anyimproved -carbonizing material 5 such as bone dust or carbonized oil.The electrodes are connected in an electric circuit, usually of lowpotential and high amperage, Whichtends toward uniformity of heatdistribution. Preferably, substantial mechanical pressure is alsoapplied to compress the carbonizing material as applying mechanicalpressure to the carbon particles makes the mass a conductor, as a whole,and hence the current cannot localize in anyone path but must distributeitself throughout the mass. By applying pressure, it is possible to usea low voltage current of high amperage, and also render the carbonizingmaterial a homogeneous conducting mass. By using a current of lowvoltage great economy in operation is effected compared with theprocesses and apparatus using high voltage or an electric arc.

In the operation of this apparatus, the

carbonizing material risesv rapidly in temperature owing to itsresistance to the The apparatusshown in Fig. `2 comprises a suitablecontainer having a lining 6 of refractory and non-conductive materialand a heating unit or grid 7 located in the container and capable ofwithstanding ahigh temperature and offering high resistance to thepassage of electric current, the grid bein connected in an electriccircuit.

n operation, the articles 8 to be carbonized are placed in vsuitableproximity to the grid and then the carbonizing material 9 is packedaround the articles, it being understoodthat initially a layer ofcarbonizing material is placed in the container and then one or morearticles arranged upon this layer and the container filled with layersof articles and carbonizing material, care being taken to have the`articles and the grid e11-Y tirely surrounded by the packing material.In this method of carrying out our process, it is not necessary that.thecarbonizing material be subjected to mechanical pressure, but on thecontrary for some pu oses it is preferable not to use pressure. to theresistance it offers to the electrical current, becomes heated and heatsthe carbonizing material by conduction, which in turn heatsdirectly thesurfaces of the arti. cles being carbonized.

The apparatus shown in Fig. 3 comprises a laminated core orelectromagnet 10 forming a closed magnetic circuit, the core beingenergized by primary windings 11 connected in the electrical circuit,and containers 12 of refractory and nonconduc'ting-material inclosingportions of the core. The articles 4 are packed around or caused toencirclethe portions of the laminated core in the containers, thecarbonizing material 5a is then packed around the articles within thecontainer and usually subjected tomechanical pressure. It is not,however, necessary or essential that the articles to be carbonizedencircle a part of the core 10 as they may be satisfactorily treatedwithin the container even though not encircling the core,

owing to the fact that the increased temperature brought about in theconductive 1 tributed in the pellets.

' magnetic {'luxinducesa secondary current in packing material iseffective conductively on such articles. The refractorylcontainers 12are lined with graphite cylinders. 12 and concentric graphite rings 12bmay bedis- In operation, the

the' articles in the container, and also in the packing material, and,owing tothe resistance offered to the current by the packing material,heat is generated.

The apparatus set forth herein are merely he grid, owing illustrative ofvarious means of carrying out our process, and it will be understood bythose skilled in the art that our process is not limited to anyparticular construction of apparatus.

In any of the instances, the heat applied is electrically generated. Inthe form shown in Fig. 1, the heat is generated by the current passingbetween the electrodes 2, 3 through the carbonizing material, and theheat is applied conductively to the surface of the articles beingtreated. In the form shown in Fig. 2, the heat is electrically generatedin the heating unit or grid 7 and transferred conductively to thecarbonizing material, and by the heated carbonizing material to thesurfaces of the article being form of apparatusshown diagrammatically inFig. 1, the apparatus shown in Fig. 4 being constructed to facilitatethe even distributiorr of the current and the resultant heat through thecarbonizer, especially where the ,apparatus is of considerable lengthfor treating long pieces of ferrous parts through which it is preferableto pass the current crosswise that is, at an angle to the ferrous parts.The container comprises an outer box or shell 15 usually of cast iron orother suitable material, a lining 1` of refractory material whichpreferably consists of sections or bricks arranged end to end andassembled within a sheet metal holder 16 which is removable from theshell 15, electrodes`2, 3 on opposite sides' of the container andembedded in the sections of the lining 1, a cover for the container, andmeans for compressing the material in the container. y

Usually, the shell 15 is formed with spacing ribs 17 on its inner faceagainst the ends of which the outer face of thel casing 16 abuts, theribs forming an air space for preventing loss 'of heat to the shell 15.A plurality of electrodes 2, 3 are arranged on opposite sides, ofthecontainer, each of nection is made with an electric circuit. The stem 20is connected to the head 18 by means of nuts 21, 22 screwing on thesternA against the front and rear sides of the head 18. The contiguousor adjacent electrodes on each 'side of the container are connected by apair of inductances 23 having like ends connected to the outer ends ofthe stems 20 of contiguous electrodes and having their other endsconnected to a feed wire 24.

The inductances serve as means to distribute the current betweenopposite electrodes irrespective loi? the resistance or conductivity ofthe carbonizing material. Suitable switches may be arranged as at 25 tocut out electrodes in theevent only a portion of the container is to beutilized and heated or if excess heat is generated in any part thereof.

26 is thecover Vfor the container, the cover being clamped in positionon the container in any suitable manner as by bolts passing throughslotted lugs 27, 28 on the container and on the cover. The meansassociated with the cover for compressing the carbonizing materiallcomprises a plunger 29, and means as screws 30 threading through thecover and having hand wheels 31 at their upper ends.

The plunger 29 consist of a 'frame 32 which is connected directly to thethreaded stems, and a plurality of sections 33 of refractory materialdetachably secured to the frame.

In operation, the articles are laid in the container etween theelectrodes andV the carbonizing material packed around articles, andwhen the current is turned onit passes through the carbonizing materialand crosswise through the articles being treated. y

The apparatus shown in Fig. 3 comprises a laminated core 10 surroundedby energizing coils 11 connected in an alternating current circuit, andcontainers 12 surrounding a portion of the core. The containers are ofrefractory and nonconductive material, are

. lined with graphite cylinders or rings and may comprise sub-divisionsor sections 35i The core is substantially horseshoe shape and isprovided with a removable section 36 at the ends lof the horseshoe for'facilitating thearrangement of circular articleson the side bars of thecore passing 'through the container. The articles are placed in thecontainer or the sections or compartments thereof after the core hasbeen' removed.

Thereafter, the core is replaced, the oppo subjected to mechanicalpressure. However,

itis not essential that the articles encircle the core as they may besatisfactorily treated within the container even though they do notencircle the core. ln the operation of this apparatus the Amagnetic fluxpassing through the core inducesa secondary current in the packingmaterial and the graphite cylinders or rings and also in the articlesthemselves, and this current generates a high temperature in the packingmaterial which effects the carbonizing. In some cases the carbonizingmaterial or pellets may be entirely eliminated, the parts to be treatedlying directly on the concentric graphite rings distributed through thecontainer. Hence, a current is passing through 'the articles at the timethey are being carbonized.

Our process is particularly advantageous in that the carbonizingmaterial and articles therein can be brought to the required temperaturein a few minutes, and it is necessary to maintain this temperature but afew minutes, as compared with hours by other processes, and furthermore,the degree of carbonization or the depth to which carbonization occursin the articles can be regulated by turning off the current through theapparatus at any desired time.

vWe have determined by photo-micrography that a case formed by ourprocess during a predetermined time, consists of pearlite of greaterdepth and contains less cementite than a case obtained by priorprocesses. For example, we obtain by our process a case of a given depthof pearlite in about one-third the time that this can be obtained by theolder method. Furthermore, due to the fact that our process requires arelatively short time, the parts treated thereby can be quenched in asuitable cooling medium directly from the carbonizer, thus dispensingwith the reheating of the parts lfor the purpose of reining the core.

What we claim is:

1. The process of carbonizing articles consisting in surrounding thearticle with a non fusible carbonizing material and quickly raising thetemperature zof such material, maintaining the same at a predeterminedtemperature for a certain length of time, and simultaneously passing anelectric current through the articles and the materialy betweenelectrodes spaced apart -from the articles by the carbonizing material.

2. The process of carbonizing articles, the same consisting insurrounding the article with carbonizing material, subjecting saidmaterial to substantial mechanical pressure and then quickly raising thetemperature of the packed material and maintaining the Isame at apredetermined temperature.

3. The process of carbonizing articles, the same consisting 1n surroundmthe article -with carbonizing material su jecting the material tosubstantialmechanical pressure to make the mass a conductor as a whole,and simultaneously applying an electric current Ito the mass ofcarbonizingy mae terial.

4. The process of carbonizing articles, the same consisting insurrounding the article with carbonizing material and quickly raisingthe temperature of such material by causing an electric current4 to passtherethrough betweenl electrodes separated from the article by thecarbonizing material.

5. The process of carbonizing articles, the same consisting in.surrounding the article with carbonizing material and quickly raisingthe temperature of such material above the critical point by passing anelectric current through thematerial between electrodes separated fromthe articles by the material surrounding the article.

6. The process of carbonizin the articles, the same consistin of surrouning the article with carbonizmg material and quickly raising the temerature of such material to 1600o to 1800o more or less by generatingheat in such articles by means of an electric current passing throughthe carbonizing material and the article from electrodes separated fromthe article by the carbonizino'y material.

, An apparatus for carbonizing articles comprising a container having alining of refractory material, electrodes exposed on the inner surfaceof the lining of each 'of two opposing sides of the container, feedWires and means connecting the feed Wires and. contiguous electrodes oneach side of the container to distribute the current between oppositeelectrodes irrespective of the resistance or conductivity 'of thecarbonizing material, substantially as and for the purpose described. A

8. An apparatus for carbonizing articles comprising a container having alining of refractory material, and electrodes'exposed on the innersurface of the lining on opposite sides of the container, contiguouselec-i trodes on each side being connected together by inductancesconnected `at like ends to contiguous electrodes and at their lotherends to a source of electrical energy supplying an alternating current,substantially as and for the purpose specified.

In testimonyI WILBR and URPHY have signed their names at Rochester, inthe county of Monroe, and State of New York, this 16 day of June, 1917,and the applicant CANNON, at Syracuse, in the county of Onondaga, and

State of New York, this 20th day of June,

whereof the applicants-

